Laser 2 on ICESat's Geoscience Laser Altimeter System (GLAS) was again successfully commanded to turn on 2/17/04 at 4:38 pm EST. It was quickly determined from GLAS instrument parameters at the Instrument Support Facility at Goddard Space Flight Center (GSFC) with support from Center for Space Research at the University of Texas that the laser was firing and the output pulse appeared normal. All other engineering parameters were nominal.
Shortly after the next orbit passed the Svalbard ground station, the first orbit's science and engineering data was received, processed, analyzed, and displayed at GSFC using ICESat's visualizer software. The engineering data showed that laser energy was leveling off a few percent higher than it was when Laser 2 was turned off in mid-November 2003. By about 8 pm yesterday, team members had determined that the science data, including the return waveform signals and received energy were all good, and that instrument algorithm improvements implemented since the last operational period were working as expected.
ICESat is expected to complete this next 33-day operational period on approximately March 21, 2004.
On September 25th, NASA's Ice, Cloud and land Elevation Satellite (ICESat) resumed measurements of the Earth's polar ice sheets, clouds, mountains and forests with the second of its three lasers. To date, the science and engineering data sent from the satellite indicates that all is well as ICESat begins its second major period of ice, cloud, and land elevation data acquisition. The mission had been "on hold" during several months of engineering review into the cause of an anomaly affecting the first laser on ICESat's instrument GLAS. NASA will issue a report shortly on the reason for the anomaly. ICESat was launched January 12, 2003, on a Boeing Delta II rocket from Vandenberg Air Force Base, Calif. On February 20th, GLAS Laser 1 was activated and on March 29, Laser 1 unexpectedly stopped working after providing about 36 days of data.
More details on the mission and its scientific and technical achievements will be available when ICESat scientists and engineers convene a special session on ICESat, this December 10th at the 2003 Fall Meeting of the American Geophysical Union in San Francisco.
For more, see Top Story/Press Release
Starting with a tracking pass over the Svalbard (Norway) ground station at 10:30 MST 2/20/03, the first steps in activating GLAS laser #1 on ICESat were taken. In the Svalbard pass starting at 15:18 MST, the laser firing commenced and firing was confirmed in real time with data from the Laser Reference System (LRS). Evaluation of the location of the laser spot was close to the expected (based on prelaunch testing). The next Svalbard pass confirmed that the laser real-time parameters were still nominal.
Confirmation that the 1064 nm (altimetry) return pulse was detected was obtained from the science data packets transmitted to the ground and processed through the Instrument Support Facility/ICESat Science Investigator-Led Processing System (ISF/ISIPS). Return waveforms look good and it appears that the laser is close to the boresight and preliminary data collection continues. On behalf of the science team, sincere congratulations and thanks are due the instrument team, spacecraft team, LASP operations team, ISIPs and ISF teams and the project team in reaching this very significant milestone!